Download SPH4U: Forces

6.
Explain. Calculate the size of the force of gravity the earth exerts on the astronaut and the force the astronaut exerts on
the earth using the expression for universal gravitation. Even if you never heard of Newton’s Third Law, why is it not
necessary to perform two separate calculations?
7.
Calculate. Your friend blasts off and travels away from the earth. Complete the table showing the size of the force of
gravity due to the earth on the astronaut at different distances from the centre of the earth. Plot a graph of Fg vs. r
Earth’s Surface
6.38 x 106 m
(0.0638 x 108 m)
6.39 x 106 m
(0.0639 x 108 m)
4.22 x 107 m
(0.42 x 108 m)
2.17 x 108 m
Space Shuttle
Orbit
Geosynchronous
Orbit
Lunar Transfer
Orbit
Moon’s Orbit
Mars’ Orbit
Fg
3.85 x 108 m
1000
|
Distance
500
|
Location
7.9 x 1010 m
0
|
1 x 108
8.
Find a pattern. Describe in words how the size of the force of
gravity varies with the separation of the objects.
9.
Reason. How far does Earth’s gravitational force extend into the universe? Explain.
|
|
3 x 108
2 x 108
distance (m)
|
4 x 108
10. Reason. Anything with mass will interact gravitationally with anything else that has mass. This means there is a
gravitational interaction between you and the person sitting beside you. Why don’t we notice this interaction? Use a
sample calculation to support your reasoning.
11. Reason. Imagine a hole is dug straight through the centre of the Earth. Describe your motion if you
were to fall in. Ignore any air resistance!
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